The fast-math package

The Numeric.FastMath module brings into scope many unsafe RULES for
Floats and Doubles that can greatly improve run time performance.
It is roughly equivalent to gcc's -ffast-math compiler flag.
Optimisation (at least -O1) must be enabled for any RULES to take effect.

These rules are unsafe because they don't strictly adhere to the
IEEE-754 regulations and may subtly change the results of your numeric computations.
See the README on github for more details.